This invention relates to a pump means, and more particularly to an eccentric type vane pump comprising a rotor, a housing rotatively containing the rotor and having a cylindrical inner peripheral surface the center of which is eccentric to the center of the rotor, and a number of radial vanes each shiftably received within a corresponding slot formed in the rotor.
In general this kind of eccentric type vane pump has a construction as shown in FIGS. 1 and 2 of the attached drawings. In the drawings the reference numeral 1 designates an end frame or bracket of an alternating current generator for an automobile not shown, 2 a shaft supported on end frame 1 by means of a bearing 3 and adapted to be driven by the alternating current generator, 2a a splined portion formed on shaft 2 at its free end, and 4 a rotor fixedly secured to shaft 2 by the engagement of splined portion 2a of shaft 2 and a splined portion 4a formed centrally within rotor 4. Rotor 4 has a number (four in the instant example) of radial slots at equi-angular intervals, each shiftably receiving a radial vane 5. A housing 6 is provided having a cylindrical inner peripheral surface the center of which is eccentric to the centers of shaft 2 and rotor 4, 7 designates a disc adapted to constitute a working chamber 15 of the pump in cooperation with shaft 2 and housing 6, 8 a seal means to hermetically seal housing 6 relative to disc 7, and 9 a seal means secured to disc 7 in contact with shaft 2 to hermetically seal working chamber 15 relative to the outside. Housing 6 and disc 7 are integrally secured together by means of a number of pins 10 so as to constitute a pump and are adapted to be mounted on end frame 1 of the alternating current generator by means of a plurality of bolts 11. 12, 13 and 14 designate an inlet port, an outlet port and a lubrication orifice, respectively, provided in housing 6, inlet port 12 being adapted to be connected to a vacuum tank not shown, and lubrication orifice 14 to a lubricating pump also not shown.
In operation, upon rotation of shaft 2 in the direction shown by the arrow, radial vanes 5 disposed within the slots formed in rotor 4 are urged radially owing to the centrifugal force applied thereto by the rotating rotor 4 so that their outer end surfaces shiftably slide on the inner peripheral surface of housing 6 so that they perform a pump action to suck air from the vacuum tank through inlet port 12 and dischange it through outlet port 13. The lubricant oil fed into housing 6 through lubrication orifice 14 lubricates the surfaces on vanes 5 and defining the slots formed in rotor 4 and is discharged through outlet port 13 entrained in the discharged air.
In a conventional eccentric type vane pump having the construction and operation as described above, when it is constituted as a pump proper as shown in FIGS. 3 and 4, i.e. the rotor 4 is not mounted on shaft 2, because the rotor 4 simply abuts the flat inside surfaces of the end wall of the housing 6 and the disc 7 without being journalled thereon, rotor 4 can freely wander about within working chamber 15 enclosed by housing 6 and disc 7. Therefore, when the pump is e.g. transported as a pump proper, vanes 5 may be damaged by rotor 4, and at the time of mounting of the pump proper onto a generator, since rotor 4 has been displaced from its proper position relative to shaft 2, the fitting of splined portion 2a of shaft 2 on splined portion 4a of rotor 4 is made difficult, resulting in possible damage to seal means 9 by the splined portion 2a of shaft 2, etc., causing a considerable decrease in the reliability of the pump means, etc.